Methods, arrangements and structures related to the technical field and character mentioned above are known earlier in a plurality of different embodiments.
As a first example of the technical background and the technical field to which the invention refers may be mentioned an arrangement adapted for spectral analysis of a sample of a gas and/or a gas mixture with a transmitting means adapted for electromagnetic radiation, a space, such as a delimited space in the form of a cavity, serving as a measuring cell and intended to be able to define an optical measuring distance, a sensing or detecting means for said electromagnetic radiation passing said optical measuring distance from said transmitting means, and at least one, to said sensing means related one or more opto-electric detectors with associated light-receiving and/or light-sensitive portions, such as chips, connected unit performing a spectral analysis of the sample of gas.
Said means, sensing the electromagnetic radiation, is opto-electrically adaptedly sensitive to the electromagnetic radiation, which is intended to fall within the spectral field whose chosen wavelength components or spectral elements are to become objects of an analysis in said unit performing the spectral analysis for determining in this unit the relative radiation intensity of the spectral element(s) for relevant and chosen wavelength portions.
Reference is here made to U.S. Pat. No. 5,009,493, German Patent Publication DE-A1-4 110 653, U.S. Pat. Nos. 5,268,782 and 4,029,521.
As a more specific first example of the arrangement analysing the sample of gas indicated here, reference is made to the contents of the published International Patent Application No. PCT/SE99/00145 (WO 99/41 592-A1), comprising a method for producing a detector related to a gas sensor and a detector thus produced.
As a second, more specific example of the arrangement indicated here, reference is made to the published International Patent Application having Publication No. WO 97/18460-A1.
As a third specific example of the arrangement indicated here, reference is made to the contents of the published International Patent Application having Publication No. WO 98/09152 A1.
Furthermore, reference is made to the contents of the International Patent Application having Publication No. WO 01/81 901 A1.
With regard to the peculiarities related to the present invention it may be mentioned that it is also known that the relative intensity of radiation of a spectral element(s) for relevant wavelength sections is low in lesser and very small concentrations of gas and that the achieved results have turned out to exhibit large margins of error.
In known units for spectral analyses normally a minimum (high) concentration of gas is required on the one hand for determining the relevant gas and on the other hand for evaluating the relevant concentration of gas therein.
It is known to supply, at right angles to a bandpass filter, electromagnetic or optical radiation having a large wave range and to create in the filter prerequisites for letting through a selected narrow wave range to an opto-electric detector so as to have in this detector, with its light-receiving and light-sensitive portion, such as a chip, and a unit connected thereto for performing spectral analysis, the intensity and/or relative intensity of the narrow wave range evaluated.
Generally, in gas test analyses over a spectral analysis of chosen wave range, it is known that different criteria provide different measuring results with varying accuracy.
Thus it is earlier known:                a. that a chosen furnished high power to the transmitting means normally increases the accuracy of the measuring result,        b. while utilizing pulse technology the transmitting means can be activated periodically in order to create prerequisites for permitting the chip of the detector to cool off between activating pulses,        c. with an increasing measuring distance through a sample of gas, between the transmitting means and the chip of the detector, to increase the exactness of the measuring result, applicable in low concentrations,        d. that different gases in a sample of gas provide different significative absorption spectra at different frequencies and/or frequency sections,        e. that different gases in a sample of gas provide a plurality of significative absorption spectra, at different frequencies and/or frequency sections,        f. that a sample of gas, placed under an overpressure, can, corrected to the atmospheric pressure, increase the accuracy of the result of the measuring,        g. that more and more sophisticated measuring units can be made to provide a more exact measuring result, and        h. that for one and the same concentration of gas there is an optimized measuring distance.        
Considering the prerequisites of the present invention and the measuring distance assigned and utilized at that time, it is known in the prior art that very short measuring distances can have the disadvantage and expose of the following drawbacks:                i. that heat energy transferred from the transmitting means to a chip of the detector causes annoying background light and/or background noise and heat, which reduces the accuracy of the result of the measuring,        j. to reduce the heating of the detector and its chip, by leading generated heat into the material of the measuring cell, to the greatest possible extent,        k. to reduce the effect of conditions, to the greatest possible extent, by synchronous detection so as to clarify the influence of the transmitter in the response of the detector,        l. to create prerequisites for subtracting noise from a detected signal in the detector and its chip to the greatest possible extent,        m. to create good mechanical prerequisites for effective cooling of the detector and its chips,        m. to create prerequisites for additionally reducing the influence of radiated heat to the detector, such as by leading heat over the sample of gas, in the cavity of the measuring cell.        
Considering the significant features related to the present invention the following prior art publications are to be mentioned.
The European Patent Publication EP-1 659 390-A1 is related to a microchip testing device (10), having an absorbance measuring chamber (25) for measuring absorbances, a transmitted light receiving unit (15) for receiving light, which has been emitted from the light source (13) and have been transmitted through the absorbance measuring chamber (25), an aperture, which extends in a straight line in the direction of an optical axis of the absorbance measuring chamber, with an entry opening for the light emitted by the light source on one end and a light exit opening on an opposite end, from which the light enters the absorbence measuring chamber, an incident light beam splitter, which is located in the optical path between the light exit opening of the aperture and the absorbance measuring chamber and which transmits a first part of the incident light and reflects another part of it, and a reflected light receiving part, for receiving the light which has been reflected by the beam splitter.
The arrangement thus described is adapted to test a liquid, and especially evaluating blood tests.
Patent Publication WO 2004/048 929-A2 is describing a high throughput screening with parallel vibrational spectroscopy.
It is shown and described a device and a method for a rapid spectrum assay of multiple samples with infrared light that may increase total light throughput.
Multiple wavelengths scan with Fouriee analysis is here combined with large numbers of sample wells located within infrared light compatible solid materials.
Very large scale measurement devices and systems for their use are fabricated from lithography and other techniques used for semiconductor processing.
FIG. 1 of Patent Publication WO 2004/084 929-A2 is showing that light from a light source (105) passes through a beam splitter (110) and is reflected by interferometer mirrors (115) into spectral filter (120).
Light from spectral filter (120) is focused via focusing and beam steering optics (125) into a bottom of a sample holder (130).
The light than interacts with each sample in one or more passes and is than reflected out of the sample holder (130) and is focused by optics (135) into an infrared camera (140).
An embodiment of this system comprises five components; 1), source of infrared radiations, 2), a device to modulate the radiation, 3), a sample holder, 4), an infrared detector, and 5) a computer to collect, process, and present the spectral data.
Patent Publication EP-0 557 655-A1 is disclosing a system for collecting weakly scattering optical signals (100) and employs a laser (102), which illuminates an unknown gas (107), contained by or within a long hollow chamber (105) having a highly reflecting coating (106 or 111).
The illuminating electromagnetic radiation (103) from the laser is directed along the entire length (L) of the chamber and collides with the vibrating molecules of the unknown gas within the containment tube.
The collisions causes the emission of shifted electromagnetic radiation (112) that is separated from the incident light and than is collected through one of the apertures (108) of the tube.
The scattered photons are than guided to a collection optics assembly (116), and a photodetector (124).
Patent Publication US-2006/119 851-A1 discloses a method and a device for measuring a concentration of a preselected gas in a gas sample.
The device comprises a “Harriott”-type multipass cell (10) having a center axis (74) and a housing (80A, 80B) surrounding and spaced from the axel to provide a tubular sample cavity (84).
The gas sample is pumped through the sample cavity via apertures (154, 156) provided in opposed ends of the axle.
A first mirror (44) and a second mirror (46) are supported at opposed ends of the axle.
A light source, e.g. a laser or LED, is provided for emitting a light beam into the sample cavity via an entry aperture (30) in the first mirror, the light beam having a wave length, at which the preselected gas strongly absorbs.
The beam is reflected between the mirrors for a number of times before exiting the cell via an exit aperture (48) in the second mirror and impinging on a detector (52).
The device further comprises a reference detector /32) for minitoring the intentensity of the unattenuated light beam and a detector for detecting the intensity of light transmitted through the second mirror after a single pass through the cell.